package demo3;

class MyCircularQueue {

    private int[] elem;
    private int front;//队头
    private int rear;//队尾

    /**
     * 构造方法
     * @param k
     */
    public MyCircularQueue(int k) {
        elem = new int[k+1];
    }

    /**
     * 入队
     * @param value
     * @return
     */
    public boolean enQueue(int value) {
        if (isFull()) {
            return false;
        }

        elem[rear] = value;
        rear = (rear+1) % elem.length;

        return true;
    }

    /**
     * 出队
     * @return
     */
    public boolean deQueue() {
        if (isEmpty()) {
            return false;
        }

        //rear = (rear+elem.length-1)%elem.length;
        front = (front+1) % elem.length;

        return true;
    }

    /**
     * 得到队头元素
     * @return
     */
    public int Front() {
        if (isEmpty()) {
            return -1;
        }
        return elem[front];
    }

    /**
     * 得到队尾元素
     * @return
     */
    public int Rear() {
        if (isEmpty()) {
            return -1;
        }

        int index = (rear+elem.length-1) % elem.length;
        //int index = (rear == 0) ? (elem.length-1) : (rear-1);
        return elem[index];
    }

    /**
     * 判断当前队列是否为空
     * @return
     */
    public boolean isEmpty() {
        if (front == rear) {
            return true;
        }
        return false;
    }

    /**
     * 判断当前队列是否为满
     * @return
     */
    public boolean isFull() {
        if ((rear+1)%elem.length == front) {
            return true;
        }
        return false;
    }
}